Essay upon the Compounds of Cyanogen. 329 



Art. XV. — Extract from an unpublished Essay upon the compounds 

 of Cyanogen ;* hy Dr. William H. Ellet, of Columbia Col- 

 lege, New York. 



Cyanuret of Potassium. — When potassium is heated in cyanogen, 

 it inflames and absorbs a portion of the gas whose volume is exactly 

 equal to that of the hydrogen, which the same quantity of the metal 

 would be capable of disengaging from water, and a cyanuret of po- 

 tassium is formed. This compound is, however, more readily and 

 economically obtained by the process of Robiquet, which consists in 

 exposing the ferro-cyanate of potassa to a long continued heat. This 

 salt, as will be hereafter shown, may be regarded, when in an anhy- 

 drous state, as a compound of cyanuret of iron and cyanuret of po- 

 tassium. At elevated temperatures and in contact with air, the for- 

 mer of these undergoes decomposition, while the latter remains un- 

 altered, but in mixture with carbon, metallic iron and oxide of iron. 

 This is to be dissolved in water, the solution filtered and evaporated 

 to dryness, and the dry mass heated to redness in a silver crucible. 

 It is then, if the operation has been properly conducted, perfectly col- 

 orless and free from iron. Exposed to heat, it fuses without decom- 

 position, and when moisture is carefully excluded, may be preserved 

 for any length of time without alteration. When acted on by water, 

 it passes into the state of hydro-cyanate of potassa, and the solution 

 is found to exert upon the animal economy an effect precisely similar 

 to that of the prussic acid ; and since it is not liable to spontaneous 

 decomposition, it may be advantageously substituted for that article 

 in the Materia Medica. The constitution of this salt is, 



Cyanogen, - 26 = 1 atom. 



Potassium, - - 40=1 " 



66 representative number. 

 The cyanurets of the other alkalies, and of the earths may be ob- 

 tained by analogous processes, and with that which I have describ- 

 ed resemble the iodides, chlorides and bromides, in the change which 



* Originally communicated to the Rutgers' Medical Faculty of Geneva College, in 

 April, 1829, and honored by their gold medal. Dr. Ellet has in hand a more ex- 

 tended investigation which may not improbably appear in the course of a few- 

 months. 



Vol. XVIII.—No. 2. 42 



